It’s called quick scoping. It takes a while to get it down, so I’d suggest going into a DM and practicing it.
Basically what I do is when I see someone is I hit mouse2 (zoom in) and then mouse1 pretty much a a millisecond after and your awp shot shoots in a straight line as if it were scoped. Learning where the shot will go without a scope can be tricky, but after some practice you’ll be good at it.
Actually no scoping is really random. I find for it to work I have to take a shot and either hit/miss someone and then just fire and it usually works. On dust2, I play mid and when they rush b I usually zoom in and get 1 or 2 people rushing b. I might not have the time to zoom in so I just shoot (without quick scoping) and I kill people. I’m not sure why it works, but it seems to work for me.