What technologies do I use to achieve "user's mouse can erase text on website" functionality?

I am developing a website and on it I'd like there to be a part where there will be some text like: "Erase this." The user will hover their mouse cursor over it (which will turn into a different cursor style), click and hold, and they will move the mouse around and the text will "erase" revealing text underneath it saying something like "Good job!" (Don't worry about the what the text says; I'm just trying to describe the overall functionality)

I have seen other websites achieve this though I don't recall which ones and I do not know how this is done.

Can someone guide me to something that will help me achieve this functionality?

Thank you!