If the admiration is directed toward you: "I'm being admired by someone." or, better, "Someone is admiring me." If you are doing the admiring: "I'm admiring someone." or "I admire someone."

It really depends on what you're trying to say. You'd normally say something like, "I'm admired by someone" or "I admire someone" or "I'm admiring it with someone". You could use the phrase "some person" as well but it doesn't sound as natural. "Admiring" implies something that you are in the act of doing so you wouldn't follow it with "by".

:)

Do you mean that 'you' are being admired by a person..?? That would be, "I am being admired by a certain person" not sure if that helps at all... ????