知道用户点击的位置

I am looking at creating a webpage with user feedback where the user can click within a certain element of the page, which brings up a comment box for the user to enter details, if the user left a note a post-it note would be left where they clicked. this note indication has to move when the user scrolls so that the note does not move away from the element it was left on.I am looking at creating a webpage with user fe