Whipworms can be found in human stool but it's hard if not impossible for whipworms to be seen in human stool with the naked eye.
You can however get tested for whipworms by taking a stool sample and having the stool sample analyzed by a lab after seeing the doctor.
You might be able to take a sample of your own feces and put it in a petri dish and look at it under a microscope but it can be hard to see with microscopes that you can buy yourself.
The labs have some pretty high powered microscopes to detect really tiny things.
So I would recommend seeing a doctor if you think you have whipworms and they will take stool sample and send the stool sample off to the lab to be analyzed.
Then the test results will let you know if you have whipworms or not.