These are called dust mites. They live in your carpet and feed off dead skin cells.
These microscopic arthropods are estimated to be only 1/4 to 1/3 millimeters long. You can only see them under a microscope, and even then, they only look like small white spider-like creatures.
On an average day, one person may shed 1.5 grams of dead skin cells, which can feed up to one million dust mites at a time.