Just like a Google account, you must check the devices that have been used to log in to your Facebook account. It is much easier to do so on a computer and below are the steps that must be taken.Sign in to your account to begin the process.
Click on the Down Arrow which is located at the top right corner.
Select Settings & Privacy by clicking on it.
Click on Security and Login.
There is a section called Where you’re logged in. It facilitates you with the information all about the logins of your account i.e devices used and their locations.
You can log out of any unwanted device by clicking on the three dots beside the device info and further either selecting Not You or Log Out.
Like a Google account, you must create a new and very strong password.