“Someone” in Chinese is 有人 (yǒu rén).
这里有人。
Somebody's in here.
Example sentence from Tatoeba (CC BY 2.0).
Not to be confused with: 诱人 (yòurén, attractive; alluring; captivating) · 游人 (yóurén, a tourist) · 友人 (yǒurén, friend)