How can I create/add a helpertext to an entry or input that opens an information modal when clicked?

Hey all I have an infolist and i want to add a preview of some sort. I thought about adding this through clicking on a specific word in the helpertext, which should result in opening a popup. Kinda like a lot of applications/web-apps have their terms and conditions on display (see the image). I would appreciate any suggestions. Thanks in advance.