How to make a Fireball move toward where the Player's mouse is?

How do you make the "Fireball" in the script below move toward where the player's mouse is?

local tool = script.Parent

tool.Activated:Connect(function()
    local fireball = Instance.new("Part")
        fireball.Parent = workspace
        fireball.Position = tool.Part.Position
        fireball.Shape = "Ball"
        fireball.Size = Vector3.new(1.5, 1.5, 1.5)
        fireball.Material = Enum.Material.Pebble
    local fire = Instance.new("Fire")
        fire.Parent = fireball
end)