Hi,
There is no default funcionality for tracking clicks instead you can use Google Analytics. Check out this thread

www.joomlaworks.net/forum/k2-en/45314-track-media-google-analytics#153263

This conversation is not related to extrafields but you can understand how this implementation works.

Are there any plans to introduce such a feature? I just need to see visitors, too much time clicking on the link.

Not really,
Since this is a user-created element, there is no way of telling how the field will be used nor the user's needs for each field.

ok