If you are asking if you can put a veneer on a crown, and then cement that crown on your tooth, there would not be very many instances where that would happen. A veneer is like a crown that only covers one side of a tooth, usually the side of the tooth that people see when you smile. A veneer is all a lab would make if that is what your tooth was prepared for.
If you mean can you get a veneer placed on a crown that you already have in your mouth, the answer is yes, but you may not like the result. When applying a veneer onto an existing crown, the tooth becomes much more bulky, and your tooth may feel too big. This is why dentists reduce teeth to place veneers, so the veneers feel natural and blend in better. It would be more ideal to have a crown replaced than to have another restoration added to it.
If you are asking you can get a crown on one tooth and a veneer on the tooth next to it, then the answer is definitely yes. When doing restorations all at the same time with the same lab, then there is a better match.