Answer:
The object of the preposition in the sentence I can stay here under the covers is the covers.
Step-by-step explanation:
Prepositions are usually followed by a noun or pronoun that acts as their object. A simple way to identify the object to the preposition is finding the preposition, putting it in the blank and asking " who or what?". In this case, the question "under what?" gives us the answer: the covers.