Take your child to the emergency room. They will see if your child's intestines are blocked and they need to take it out. Otherwise your child will just have to pass out the marble. In the future keep anything that can fit inside a toilet paper tube away from him.
Having much experience with this, with my kids, not me, lol, the general consensus among doctors is to just make sure that it comes out the other end. Not a glamorous job, but someone needs to do it, and actually see proof.
Call your pediatrician they will likely tell you that it will eventually pass in their bowl movement and they will tell you to watch the movements for the marble to ensure it passes in a timely fashion. They may suggest giving him something to encourage the bowl movement. They may also have you come in to ensure no obstruction.
