In 2013, Facebook acquired a company which makes a VPN client named Onavo Protect. The social network is now pushing the app on iOS devices to track user activity and collect data. First spotted by TechCrunch, you can find the option as a new menu item in Facebook’s iOS apps. Clicking on it, you’ll be directed to App Store and “Onavo Protect – VPN Security” page will be opened. Don’t install it, obviously. That is a “Spyware”.
— source fossbytes.com