You'd need to query for that using CB Query Field. Media is stored in the _comprofiler_plugin_gallery_item table. Albums are stored in _comprofiler_plugin_gallery_folders. Both tables provide datetime of when the media was created so you can use that to query for the most recent media entry and return the date as a result. Example as follows.
Code:
SELECT `date` FROM `#__comprofiler_plugin_gallery_items` WHERE `user_id` = '[user_id]' ORDER BY `date` DESC LIMIT 1
That'd return the date of the most recently uploaded media from a user. It does not have asset specified so it'll check from every gallery. You'll need to specify asset in the WHERE statement if you need it to be more specific. You can format the date using SQL functions as needed as it won't be formatted like regular date fields on output (will be SQL 0000-00-00 00:00:00 format).