I have suggest some tips for know if someone is spying on my computer mac:
Click on your Apple icon & select Software Update to install software and security updates on your Mac.
Click and Finder and select Applications from your sidebar.
View the installed applications & research any program that looks unfamiliar or suspicious.
Select any application and press Command-Delete to remove the program from you mac.
Press Command-Space & type Activity Monitor and press "Enter."
View the running processes & research any program that looks unfamiliar or suspicious.
Select a process and click "Quit Process" to kill any programs that may be a threat.
Scan your computer, This is a normal way to check your computer status for any tracking or spyware applications has been affected.
Open your Applications & check all applications if there are any you don't recognize or you don't remember installing immediately uninstalled and Trash icon on your desktop.
Secure your computer by completely wiping and reinstalling the operating system after performing a basic backup of your files.