Being able to control your baby chicks early on is a very useful thing and teaching them other things hinges on being able to get them to come to you when you want.
Using food accomplishes wonders, and all you have to do is use the same verbal and visual cues each time you offer treats. In no time at all, your chicks will respond when you call them using these cues.
I've developed a visual cue, though, that I can use with or without food. It comes in handy when I need them to come to me and I don't have time to grab some treats to bribe them. When they're still just a couple weeks old, I hold a treat in my fist and point to in by "pecking" at my hand with my index finger of the other hand. Then I slowly open my fist to expose the treat. They quickly associate seeing my closed fist with there being food in it, and they will come running. After a while it doesn't matter there's no food in my fist. I just only need to point to it and they think there is.
If you want to get your chicks to come out from under the coop, or come into the pen, you only need to call them and point to your closed fist.
To get them to go into the coop at night, wait until you hear them making "bedtime" noises. It sounds like crickets chirping, very soft. They're ready to go inside. Get into the coop and call to them rather than trying to catch them and stuff them inside. You might need food the first time to interest them. Wave the treat at them from inside the coop entrance. Use a small flash light if it's darker inside the coop than outside. Chicks are fearful of going into a strange place where they can't see what's in there. A nightlight might help, too, at least until they go in on their own.
It's so much easier to teach chicks to go into the coop by calling them in than by grabbing them up and shoving them through the pop hole, and they learn in a matter of just a few days. Mine were going in on their own by age five weeks.