Intel ME can be used to monitor employees without the OS ever becoming aware of anything. The only way to detect it would be to sniff the network.
Although, probably a lot of large corps aren't too different.
I’m sure such a thing is out there, but I doubt it’s being used by employers to spy on workers. More like governments spying on workers with access to sensitive IP.
https://en.m.wikipedia.org/wiki/Intel_Active_Management_Tech...
Plus the laptop "anti-theft" BIOSes that phone home whose name I cannot recall.
Absolute Computrace starts at $29 and is resident in most every OEM BIOS manufactured in the last 20-25 years.