Hello and hope you are doing well.
It could be a pimple, but this would cause pain. Other causes could be due to Keratosis Obturans, sebaceous cyst or tumor. It could also be due to an infection of the external ear or otitis externa. A physical examination may help determine the cause. If needed blood tests and X ray may help. You will need to consult your primary care physician for further evaluation, who may then refer you to an ENT specialist.
Hope this helped and do keep us posted.