If you suspect that your Facebook account is compromised, you must change your password immediately. Then, if you use Facebook to log in to apps such as Spotify or Instagram then change those logins as well. This will prevent hackers from accessing these third-party services via your compromised Facebook account.
Hackers can discover an abundance of personal information in hacked Facebook accounts. Hackers can make use of this information for nefarious purposes, such as taking credit card numbers and sending people fake credit card offers or scams that involve phishing. Hackers can also use compromised accounts to send spammy messages or post on your timeline (as the case were you who was responsible).
Hackers are likely to gain access to an account through exploiting a weakness in the Facebook app’s code. A bug in the iOS Facebook application allows hackers to take over cookies, and steal the “access token” of an iPhone user. These tokens, which are digital keys, grant them full control over the user’s Facebook Account, as well as any other websites they sign into with their Facebook credentials.
Hackers can also gain access to accounts by using brute-force attacks. This technique involves guessing passwords, usually the most commonly used ones like 1234567890 or 123456789. Hackers also gain access to accounts by scanning compromised credentials. There are several free tools to scan https://www.app-ink.net/how-to-use-pool-host-to-create-multiple-hosts for stolen data, such as the popular site HaveIBeenPwned.