Mark Zuckerberg seen covering up his webcam in picture celebrating Instagram milestone

The Facebook CEO was trying to celebrate the fact that Instagram had got to 500 million users – but accidentally revealed a little more than he’d expected about himself

Mark Zuckerberg celebrates 500 million users on Instagram – but that was far from the most interesting thing about the picture

Mark Zuckerberg knows a lot about getting to know people through their computers. So a tiny piece of tape attached to his laptop might also be a terrifying warning.

The Facebook founder and CEO has been spotted with a piece of tape covering up his webcam and microphone in what appears to be a way of stopping his computer from spying on him.

Mr Zuckerberg’s DIY privacy protection was spotted in a picture – first pointed out in a tweet by Chris Olson – that was intended to celebrate Instagram reaching 500 million monthly users. But it has become far more scrutinised because of something else.

In that same picture, what appears to be Mr Zuckerberg’s computer can be seen. And on the top is a small piece of tape, as well as something else covering up the microphone jack in the side.

Both are presumably ways of keeping prying eyes out, covering up the two ways that a computer can get a sense of what is happening around it. Mr Zuckerberg is one of the highest-profile security targets in the world – in real life as well as on the internet – and so what may appear to be paranoia is probably a sensible way of preserving privacy.

Mr Zuckerberg is far from the first person to worry about the power of the cameras that are watching us at all times. Edward Snowden has warned of its power as a way of surveilling people, and FBI director James Comey has said that he has taken advice to cover up the camera to keep people from seeing him.

"I saw something in the news, so I copied it,” Mr Comey told an audience earlier this year. “I put a piece of tape — I have obviously a laptop, personal laptop — I put a piece of tape over the camera. Because I saw somebody smarter than I am had a piece of tape over their camera."

The FBI itself is reported to have used technology that can hack into webcams and allow it to spy on targets. And away from law enforcement, hackers have repeatedly broken into webcams and used them as ways of spying on and then extracting money from people.

MacBooks, which is what Mr Zuckerberg works on, have their cameras hard-wired so that whenever the camera is activated a little green light shows up next to them. But that safety measure has been circumvented in the past, and can only be seen when sat in front of the computer – meaning that covering it up with tape is the only way to be entirely sure that it isn't being used to see through.

Some had initially suggested that the desk might not be Mr Zuckerberg’s. But gadget blog Gizmodo pointed out that he has done numerous announcements and videos from the same seat.

It isn’t clear why Mr Zuckerberg wrapped up his microphone jack with what appears to be either tape or a special plug.

The power that the devices on our desks and in our pockets have to monitor us was demonstrated earlier this month by the suggestion that Facebook was able to listen in on microphones. Facebook fiercely denied the rumour.