How to get the row and column number of a Heatmap cell the mouse is pointing at?

I'm displaying a heatmap in one of the ui panels in my GUI (created using GUIDE), and I would like to be able to click on any of the cells in the heatmap and have the corresponding data plotted on a seperate figure. The part I can't figure out is how to create a ButtonDown callback which could get the row and the column number of whichever cell the mouse is pointing at. I know this should be possible as the heatmap already displays this inforamtion when the mouse hovers over the cell (see attached image), but I could not find a way to access it.

So I was wondering if anyone knows a way of getting that information from the heatmap? If that is not possible how should I go about tracking the mouse to get the row and column it's pointing at?