By using this Advanced Setting the system will first attempt to use a member's profile cover photo as the social share image:
Prioritize Profile Cover Photo As Social Share Image
System Variable: profile_share_cover_photo_priority
**Important: Ultimately Facebook and other social networks will decide to use the profile cover photo if the image dimensions meet the minimum criteria. If the criteria is not met, then social networks will choose the next qualifying image on the page as the social share image.
Once the member uploads the Profile Cover photo it will show up on member's profile like this:
If the Advanced Setting is turned on and the member shares the profile on facebook the Profile Cover will be used as the post image: