How do i change my code so that instead of pressing c you have to click with mouse?

I want to make a code where a player can use a tool that activates when you have it out and left click to shoot out a electric bird in front them. I have a script that shoots out a electric bird when the player presses c while holding the tool.

In starter pack i have a tool call Thunder Bird. In the tool i inserted a string value called Active and a string value called Equip. I also have a local script in the tool.

--- Equip/UnEquip
local Tool = script.Parent

Tool.Equipped:Connect(function()
	Tool.Equip.Value = true
end)

Tool.Unequipped:Connect(function()
	Tool.Equip.Value = false
end)

--- Skill
local UIS = game:GetService("UserInputService")
local plr = game.Players.LocalPlayer
local Mouse = plr:GetMouse()
local Debounce = true
Player = game.Players.LocalPlayer
Animation = Instance.new("Animation")
Animation.AnimationId = "rbxassetid://4608419697"

UIS.InputBegan:Connect(function(Input)
	if Input.KeyCode == Enum.KeyCode.C and Debounce == true and Tool.Equip.Value == true and Tool.Active.Value == "None" then
		Debounce = false
		Tool.Active.Value = "HieShock"
		wait(0.1)
		Track1 = Player.Character.Humanoid:LoadAnimation(Animation)
		Track1:Play()
		wait(0.15)
		script.Fire:FireServer(plr)
	local hum =  Player.Character.Humanoid
	for i = 1,30 do
		wait()
		hum.CameraOffset = Vector3.new(
			math.random(-1,1),
			math.random(-1,1),
			math.random(-1,1)
		)
	end
	hum.CameraOffset = Vector3.new(0,0,0)
	    wait(0.15)
		Tool.Active.Value = "None"
		wait(2)
		Debounce = true
	end
end)

in the local script i have a remote event named Fire and a script called Skill in the remote event Fire

script.Parent.OnServerEvent:Connect(function(plr)
	local Alive = true
	local Projectile = game.ReplicatedStorage.HieDF.HieShock.IceBird:Clone()
	Projectile.Parent = workspace
	Projectile.CanCollide = false
	Projectile.Anchored = false
	Projectile.CFrame = plr.Character.HumanoidRootPart.CFrame * CFrame.new(0,4,0) * CFrame.fromEulerAnglesXYZ(0,0,0)
	Projectile.Touched:Connect(function(hit)
		if hit.Parent:FindFirstChild("Humanoid") and hit.Parent.Name ~= plr.Name then
			hit.Parent.UpperTorso.Velocity = plr.Character.UpperTorso.CFrame.UpVector * 125
			local HitEffect = game.ReplicatedStorage.HieDF.HieShock.ShockwaveFX:Clone()
			local ShockwaveFX = game.ReplicatedStorage.HieDF.HieShock.ShockwaveFX:Clone()
			HitEffect.Parent = workspace
			HitEffect.CFrame = hit.Parent.HumanoidRootPart.CFrame
			ShockwaveFX.Parent = workspace
			ShockwaveFX.CFrame = hit.Parent.HumanoidRootPart.CFrame
			HitEffect.CanCollide = false
			HitEffect.Anchored = true
			hit.Parent.Humanoid:TakeDamage(5 + plr.Data.DevilFruit.Value)
			Projectile:Destroy()		
			for i = 1,25 do
				wait(.05)
				HitEffect.Size = HitEffect.Size + Vector3.new(0.5,0.5,0.5)
				HitEffect.Transparency = HitEffect.Transparency + 0.1
				ShockwaveFX.Transparency = HitEffect.Transparency + 0.1
			end	
			HitEffect:Destroy()
		end
		if hit.Parent:FindFirstChild("Enemy") and hit.Parent.Name ~= plr.Name and hit.Parent.Enemy.Health >= 0 and Alive == true then
			hit.Parent.UpperTorso.Velocity = plr.Character.UpperTorso.CFrame.UpVector * 125
			local HitEffect = game.ReplicatedStorage.HieDF.HieShock.ShockwaveFX:Clone()
			local ShockwaveFX = game.ReplicatedStorage.HieDF.HieShock.ShockwaveFX:Clone()
			HitEffect.Parent = workspace
			HitEffect.CFrame = hit.Parent.HumanoidRootPart.CFrame
			ShockwaveFX.Parent = workspace
			ShockwaveFX.CFrame = hit.Parent.HumanoidRootPart.CFrame
			HitEffect.CanCollide = false
			HitEffect.Anchored = true
			hit.Parent.Enemy:TakeDamage(5 + plr.Data.DevilFruit.Value)
			Projectile:Destroy()
			if hit.Parent.Enemy.Health <= 0 then
				Alive = false
				--Kill rewards
				local Leader = plr:FindFirstChild("Quest")
				plr.Data.Beli.Value = plr.Data.Beli.Value + game.ReplicatedStorage.KillRewards:FindFirstChild(hit.Parent.Name).Beli.Value
				plr.Data.Exp.Value = plr.Data.Exp.Value + game.ReplicatedStorage.KillRewards:FindFirstChild(hit.Parent.Name).Exp.Value
				if Leader.Type.Value == game.ReplicatedStorage.KillRewards:FindFirstChild(hit.Parent.Name).Type.Value then
				if Leader ~= nil then
				Leader.Amount.Value = Leader.Amount.Value + 1
				Alive = true	
			  end
			 end
			end			
			for i = 1,25 do
				wait(.05)
				HitEffect.Size = HitEffect.Size + Vector3.new(0.5,0.5,0.5)
				HitEffect.Transparency = HitEffect.Transparency + 0.1
				ShockwaveFX.Transparency = HitEffect.Transparency + 0.1
			end	
			HitEffect:Destroy()
		end
	end)
	local BV = Instance.new("BodyVelocity",Projectile)
	BV.MaxForce = Vector3.new(math.huge,math.huge,math.huge)
	BV.Velocity = plr.Character.HumanoidRootPart.CFrame.LookVector * 110
	wait(0.75)
	BV:Destroy()
	wait(0.25)
    Projectile:Destroy()
    end)

In replicated storage i have a folder called HieDf and in that folder i have another folder called HieShock that has a mesh part called IceBird that is the bird that gets shooten.

As zamd157 stated, Button1Down is deprecated, instead we are going to use MouseButton1 of UIS.

local uis = game:GetService("UserInputService")

local player = game.Players.LocalPlayer
local char = player.Character
local humanoid = char:WaitForChild("Humanoid")
local mouse = player:GetMouse()

local deb

local anim = Instance.new("Animation")
anim.AnimationId = "rbxassetid://4608419697"

local tool = script.Parent

tool.Equipped:Connect(function()

    tool.Equip.Value = true

end)

tool.Unequipped:Connect(function()

    tool.Equip.Value = false

end)

uis.InputBegan:Connect(function(key)

    if key.UserInputType == Enum.UserInputType.MouseButton1 then -- If left click is clicked

        if not deb then return end
        if not tool.Equip.Value then return end
        if tool.Active.Value ~= "None" then return end

        deb = true
        tool.Active.Value = "HieShock"

        wait(0.1)

        local track1 = player.Character.Humanoid:LoadAnimation(anim)
        track1:Play()
        
        wait(0.15)

        script.Fire:FireServer()

        for i = 1,30 do

            wait()

            humanoid.CameraOffset = Vector3.new(
                math.random(-1,1),
                math.random(-1,1),
                math.random(-1,1)
            )

        end

        humanoid.CameraOffset = Vector3.new(0,0,0)

        wait(0.15)

        tool.Active.Value = "None"

        wait(2)

        deb = false

    end
end)

Good luck, if you encounter problems, comment down so I can check.