Cursor position not mouse position in Input text box

I have an Input Text area that users can edit and then submit. I need to be able to show, on screen, the cursor’s current position as they type. I don’t need to know where the mouse is but all work-arounds I’ve found so far can only tell me the mouse position. The font for the text is ‘courier’ or ‘courier new’ and the Input Text area is scrollable. Can anyone suggest a solution?

Cheers

Steve