Your party affiliation in your voter registration is public info depending on state (maybe even nationwide), no one will know your personal vote except being able to make a good guess based on your registration.

The NSA collects tons of data and most likely your only flagged in some database as a potential commie and maybe even a PSL likely voter; FBI, CIA, border agents can probably pull it up but no one is gonna care or do anything unless the American left gets way more based in the next couple years.