My yorkie sleeps in a crate beside the bed. When he was a puppy, I had the door on the crate. I could hear him if he needed to go out. Now he is 2 years old. The door was taken off long ago. If it is a cold night, he uses the crate as a step and jumps up on the bed to snuggle next to me. Often under the covers.
If he needs to go out, he will wake me with a whine or by standing on me...
He will occasionally use a paper pad that I leave in the hallway and one beside the door to go outside. I also take him out first thing in the morning. It takes a long time to train these little ones. Try to be patient and consistant...it will eventually pay off.