my sewer trap has two vertical pipes with two caps,one a little smaller than the other. I recently unclogged the drain by opening both caps. The smaller cap apparently fell into the larger pipe(hole)It is now causing a minor blockage which I have to clear everyday with a piece of wire. I can't see the cap but can feel it inside and hear that hallow gulping sound whenever toilet flushes. How can I retrieve that cap.I tried a magnet but it nothing happened as it seems is non magnetic.
I really don't have money and don't want to go the expensive way unless it is a last =resort.
Thank oyu.

I can't really envision what caps you speak of but my suggestion would be to wrap a piece of flexible wire around a cloth then make the cloth into a ball that will go down the pipe.
Wrap the cloth ball with double sided carpet tape. That should give you a soft sticky ball. If the cap is not too heavy and the sticky ball comes into contact with the cap, you may be able to pull it out.

Are you on slab or raised foundation ?
Can you snap a picture of those 2 clean outs and post it for us ?
Back to you...

Could you try a Shopvac?