How do you hack a person in Watch Dogs Legion?

Question

I have recently bought a game by Ubisoft called Watch Dogs Legion. It is great fun, except that I can't hack people. There is a guard that has the keycodes I need and when I tried to figure out how to get it from him the answer I found was to hack him. The video I saw showed this was possible through a camera. I hacked a camera, zoomed in on him and there is no option at all to hack him. I then went in and killed him and still wasn't able to hack the keycode from him. What am I doing wrong? He's the only way to get the keycode and I can't find ANY way to get it from him. This is in the Buckingham Royal Mews area.