If you post a photo on Facebook and your privacy settings prevent the public from seeing it, there is no way for anyone other than your friends to view it.

Question

Quizplus · Accepted Answer

Even with strict privacy settings, there are ways someone outside your friend list could potentially see the photo, such as through shared friends' activity, security vulnerabilities, or if the photo is reported and reviewed by Facebook staff.

If You Post a Photo on Facebook and Your Privacy