Ensure your photo albums are set to "Friends" rather than "Public."
While you cannot force a private profile open, there are standard ways to find information that is already accessible: facebook profile private pictures unlocker viewer
You're told to complete a "verification" step — downloading an app, completing a survey, or entering your phone number. The scammer earns commission per survey or sells your number to telemarketers. You never get the photos. Ensure your photo albums are set to "Friends"