Custom Field On Postbit?

[MultiSync77F]

I created a custom private field for my users that stores their customer number. I want my administrators to be able to view the field without going into the profile each time, so I would like to make a new icon next to the report post icon. When they hover over the icon with the mouse it displays the data in the customer field in a tooltip, or displays "No Information Avaliable" if the field is empty. The same thing that happens when you view an IP Address, however when you click the customer id button, nothing happens I don't need that much function.

How can I do something like this?