ReiKey and Task Explorer from Objective-See

Objective-See is a non-profit 501(c)(3) corporation that develops free and open-source security software for the Mac. Two of its better-known programs are BlockBlock and KnockKnock, utilities to monitor any persistent applications installed on your device and to provide real time scanning for malware. It's free firewall, Lulu, is also very popular. See this review from Oliver Pifferi.

Two other worthy apps to download and use are ReiKey and Task Explorer.

ReiKey

 
Malware and other applications may install persistent keyboard "event taps" to intercept your keystrokes. ReiKey can scan, detect, and monitor for such taps. In other words, it looks for and detects keystroke interceptors installed on your device. it will find and report legitimate software like Better Touch Tool, Keyboard Maestro and Text Expander but it will also find malware like Xcode Spy and other keyboard hijackers.

Task Explorer

Task Explorer is like Apple's Activity Monitor on steroids. it explores all the tasks/processes running on your Mac and shows:

• Signing status
• VirusTotal integration
• Loaded dynamic libraries
• Open files
• Network connections
• Global search