What is a good approach to detect object change by mouse hover?

Hello, I've been developing a script that when the mouse left button is held down, a value is incremented until the left button is released. My goal is that while the mouse is down and simultaneously if the object that the mouse is hovering over changes, the value would be reset to zero, and would still increment. The following is my code/ attempt:

local Player= game.Players.LocalPlayer
local Mouse= Player:GetMouse()

local holdSwitch= 0
local holdVal= 0

--compares difference between object 1 and 2
local obj1= Mouse.Target.Position
local obj2= Mouse.Target.Position

local screenGUI= Instance.new("ScreenGui",game.Players.LocalPlayer.PlayerGui)
screenGUI.Name= "screenGUI"
--GUI for holding down mouse key
local textLabelHoldMouse= Instance.new("TextLabel",screenGUI)
textLabelHoldMouse.Name= "HoldMouse"
textLabelHoldMouse.Position= UDim2.new(0,10,0,400)
textLabelHoldMouse.Size= UDim2.new(0,150,0,25)
textLabelHoldMouse.BorderSizePixel= 0
textLabelHoldMouse.BackgroundTransparency= 1
textLabelHoldMouse.TextColor3= BrickColor.White().Color
textLabelHoldMouse.Text= "Hold: "
textLabelHoldMouse.TextXAlignment= "Left"
textLabelHoldMouse.TextTransparency= 0--toggle

--detection script
local vb= 0
Mouse.Button1Down:connect(function()	
	--with distance if; numMode indicates build or destroy
	if workspace.numMode.Value== 0 and tostring(Mouse.Target)== "DirtBlockClone" and Player:DistanceFromCharacter(Mouse.Target.Position)< 16 then	
		Mouse.Button1Up:connect(function()--stops count and resets holdVal
			holdSwitch= 1
			holdVal= 0
			--textLabelHoldMouse.Text= "Hold: "..holdVal
		end)
			
		holdSwitch= 0
		while holdSwitch== 0 do
			wait(0)
			holdVal= holdVal+1
			textLabelHoldMouse.Text= "Hold: "..holdVal
			if not obj1== obj2 then
				holdVal= 0
			end
		end
	end
end)

So, I instantiate a comparison for each step of the wait interval, and it would test if the object target position has changed. I'm not sure what is going wrong.