I have a couple of cats who just run under their couch as soon as they hear a noise that they don't like or someone enters the house. If they can't get there, then they go under the spare bed which has an even narrow gap than the couch. Most will come out once they feel secure again, which usually just entails me talking with them as soon as the person has gone or the noise has abated. The easy ones will also come out for food. But Rosie....well!!!! I stuggled with this for about two years. She would miss meals galore rather than venture out. Got to the point where if I hadn't fed her breakfast in time, she would just go there anyway, without noise or people. Great big safety blanket! Rosie LOVES to be combed. On one occasion, I had tried all the usual ways to get her out from the couch and had sat down on it to try and think of another way to get her out. One of my other cats came up to me and as I happened to have the comb with me, started to comb him. Within a minute of Rosie hearing the sounds of a cat being combed, she was out from the couch! It was at that moment, I started to curse myself for not having tried it sooner!! Now, providing the reason she went under has abated, I can get her out by just running my nail through the teeth of the comb. Also gets her in the house a lot quicker!!
I'm not saying that this is going to work for you - to start with your cat would really have to love a good combing and not all do - but if you find some activity that your cat is really interested in, you may get good results. But you will need to remain calm the whole way through and consider why the cat is there in the first place. For example, if the cat goes under the couch when you need to take it to the vet, you would be better off isolating the cat in a room away from where it can hide with sufficient time for it to settle itself before you try putting it in a carrier. My older cats always hide when they see the cat carrier but the younger ones don't - they like to go in and explore, and will curl up in there sometimes too, so familiarity with a carrier when it isn't needed can also allieviate the stress when it needs to be in one, and thus the need to hide is negated.
HTH