Unlockable first person cursor?

I'm working on a "horror" game and I want the player to be able to unlock the mouse cursor by pressing LeftControl but remaining in first person as featured in "get a snack at 4am"

https://www.roblox.com/games/6165106805/get-a-snack-at-4-am

I already have my simple first person lock of course:

player = game.Players.LocalPlayer
player.CameraMode = "LockFirstPerson"

But how can I force the player to remain in first person but allow for the cursor to be moved upon pressing LeftControl?

there's something called Modal in TextButton you can use that by making it invisible and making Modal true.

if you need the code here:

local modal = false

game:GetService("UserInputService").InputBegan:Connect(function(input, typing)
	
	if typing then return end
	
	if input.KeyCode == Enum.KeyCode.LeftControl then
		if modal == false then
			modal = true
			TextButton.Modal = true
		else
			modal = false
			TextButton.Modal = false
		end
	end
end)