Quote:Apple's MacBooks that feature the new T2 Security Chip come with a hardware disconnect designed to automatically disable the microphone, as first discovered by TechCrunch's Zack Whittaker.

Apple's T2 Security Chip bundles a Secure Enclave coprocessor, designed to power the macOS APFS encrypted storage, Touch ID, and secure boot on all Macs. Furthermore, the security chip also features a number of controllers which on Macs that do not feature a T2 chip are found on the motherboard, namely the system management controller, SSD Controllers, audio controller, and the image signal processor.

As detailed in the "Apple T2 Security Chip Security Overview" document published in October 2018, "All Mac portables with the Apple T2 Security Chip feature a hardware disconnect that ensures that the microphone is disabled whenever the lid 
is closed." Because this microphone disconnect is implemented on a hardware level, no software is capable of using the microphone to eavesdrop on the user when the MacBook's lid is closed, even if it runs with kernel or root privileges.