If you need to see a cover photo that is still public (even on a restricted account), these are the only safe methods: Lock your Facebook profile | Facebook Help Center
Exclusive Guide: Understanding "FB Locked Profile Cover Photo Viewer" Tools fb locked profile cover photo viewer exclusive
: "Exclusive" software downloads frequently contain spyware or adware. If you need to see a cover photo
When someone locks their profile, Facebook applies a "limited view" for anyone not on their friends list: fb locked profile cover photo viewer exclusive
: Using automated scrapers to access private data violates Facebook's Terms of Service. Legitimate Ways to View Public Content
: Non-friends can only see a small, low-resolution version of the current profile and cover photo.
: The option to click and view these photos in full-screen mode is disabled for non-friends.