You can do the following. The skills of coding are welcomed....
- install the plugin ACF
- create a field "image" (can return an array or link)
- apply a field to the menu item.
- create a custom walker for the menu that have pictures for each menu item.
- and then it remains to integrate this whole thing in html, css, php
Another option is a paid plugin for ubermenu. Not sure this is what you need... but it can pokazyat pictures for each menu item...