How to get the time on the point that you click on the clock?

Question

For instance, when you click the clock on the screen, there will pop up a notification/dialog which displays the exact time point. Anyone can tell me how to achieve this function? Thanks in advance!

Maybe I should explain the "exact time point" . For example, there is a big analog clock on the screen. When you click around the dial, it will pop up a dialog box to display the exact time.