Identifying who has logged into your system in Linux is way easier than Windows Operating System.
In Linux System whenever someone tries to log in using SSH is recorded by the log file, the log file is located in /var/log/auth.log. location can be different in other distribution.
If you not found auth.log file in your system try to execute the below command to view the log from systemctl.
journalctl -u sshd |tail -100
-u (Show the user journal for the current)
sshd (SSH user created by system by default)
tail -100 (Print top 100 result from log file)