Hi enzimas,
I am sorry but that’s not possible with either the free or Pro version.
The only way I can think to do it would be to code a custom widget that handles the display of the whole sub menu (the links, the image, and handle the image swapping). Unfortunately I am not aware of any widget plugins that can do that.
PS Although this isn’t strictly a pro related question, if you do have a Pro related question in future please get in touch through https://www.megamenu.com/support/ (we are not allowed to discuss the commercial side of things on these forums). Thanks!
Regards,
Tom