Press the Power + Volume Down buttons at the same time.
Before looking for workarounds, it’s important to understand exactly what Facebook’s Profile Lock does. When someone locks their profile: download facebook cover photo of locked profile
If you have a legitimate reason to view or download their cover photo—whether for personal, professional, or sentimental purposes—sending a polite message or friend request is by far the best approach. The only 100% safe way to see someone’s private content is to ask nicely. Press the Power + Volume Down buttons at the same time
Standard context menus for saving images are disabled on the asset layers. The only 100% safe way to see someone’s
: This stops identity theft and unwanted downloading. The "mbasic" Browser Trick
Warning: Never use tools that require you to log into your own Facebook account or download external .exe software. These are often phishing scams designed to steal your credentials. Maximizing the Quality of Downscaled Images