1.
If a person is sniffing around, they are trying to find out information about something, especially information that someone else does not want known. (INFORMAL)
But really, what harm could it possibly do to pop down there and just ~?...
A couple of plain-clothes men had been sniffing round his apartment.
= nose around
PHRASAL VERB: V P, V P n
2.
If a person or organization is sniffing around someone, they are trying to get them, for example as a lover, employee, or client. (INFORMAL)
When I had to go away to university, I was convinced that other men would be sniffing round her...
PHRASAL VERB: no passive, V P n