According to the customs and border protection website, there is a max limit of $200 that is free from duty and tax, and it has to be for personal/household use. There are amount limits on alcohol and tobacco.

But if it’s something like a single phone, you pay in cash and open it there and dispose of the packing material. Yes, you could easily get away with violating those restrictions in most cases.

Side-note: The limit is $800 if you go to the Caribbean, and up to $1600 for places like US Virgin Islands