Care to clarify yourself a bit more?
BCC addresses are not exposed so you can "secretly" address more people in
an email.
When you receive an email there is no way to tell who has been BCCed on the
message so you won't be able to replies aren't send to BCCed members.

Use any target field you want (To, Cc, or Bcc).  Just send the e-mail
to that one person.  Doesn't matter which field you use.

If you mean can you send something additional to the BCC person that the TO
person won't see, then no, they get the exact same message.