how do you create a ray casting script that keeps going until button is released?

ive made a raycasting tool that shots when you click it but i want to know how you make it last until released.

local tool = script.Parent
local player = game:GetService("Players").LocalPlayer

tool.Equipped:connect(function(mouse)
    print("Tool equipped!")

    mouse.Button1Down:connect(function()
        print("Mouse pressed!")
        local ray = Ray.new(tool.Crystal.CFrame.p, (mouse.Hit.p - tool.Crystal.CFrame.p).unit * 300)
        local part, position = workspace:FindPartOnRay(ray, player.Character, false, true)

        local beam = Instance.new("Part", workspace)
        beam.BrickColor = BrickColor.new("Toothpaste")
        beam.FormFactor = "Custom"
        beam.Material = "Neon"
        beam.Transparency = 0.25
        beam.Anchored = true
        beam.Locked = true
        beam.CanCollide = false

        local distance = (tool.Crystal.CFrame.p - position).magnitude
        beam.Size = Vector3.new(0.3, 0.3, distance)
        beam.CFrame = CFrame.new(tool.Crystal.CFrame.p, position) * CFrame.new(0, 0, -distance / 2)

        game:GetService("Debris"):AddItem(beam, 0.1)
    end)
end)