There are several ways to detect a keylogger on a mac, from simply reviewing the processes running on the computer to using a mac os spy detection program.
Step 1 Open the Activity Monitor to check for unknown process. This system tool will allow you to view the programs (processes) currently running on your computer.
Step 2 Check and Research any unfamiliar processes running in your “Activity Monitor.” Critical system processes sometimes have unrecognizable names, however, and keyloggers may have a name that sounds legitimate.
Step 3 Download and install a mac keylogger detector or another software firewall. This type of mac software alerts you when another program tries to connect to the Internet. It will detect a keylogger for mac before it sends information over the Internet, and allow you to block it.