Mark Zuckerberg recently posted a photo with his computer in the background. The Facebook CEO is paranoid about hackers tapping into not only his webcam, but his microphone. Connect a pair of earbuds with a built-in mic into your 3.5mm audio jack, then snip off the earbud with the mic on it. When you sever the line to the microphone, the computer doesn’t change back to the internal mic, and it can’t receive any audio from the (now missing) external mic.”]
Source: https://mashable.com/article/computer-microphone-hack