FACEBOOK PRIVACY QUESTION?

[dozen]

a person whom I know,he is not one of my friends on facebook, has told me that he can access my account hidden content. and he can view my pics and albums even though the privacy settings limit the access to such content (only friends can view it!). actually I didn't believe him but he appears to know many things ....how many albums I have, the names, some details about the pics I have. I don't know how did he get all that. I thought that he may asked one of my facebook friends about these things!! I really confused. is there a bug or an add-on or let's say a hacking tool that allow him to access the private information of me?? please help me