Somethng is mandatory. 'On' fits well: also "snoop into people's lives". We spy on , but we snoop into .
New words, one handy idiom, and a 2-minute quiz — delivered to your inbox to keep your streak alive.
New2grammarIf you don't mind, what's the difference between snoop on, snoop into, and snoop around?I believe we do not 'snoop on'.