I would check with an attorney. Wiretap laws generally only cover communications--the spoken (or in the case of electronic communications, the written) word. BUT there are laws concerning invasion of privacy that might be implicated in a place where someone has a legitimate expectation of privacy. Whether that would cover a childcare provider in YOUR home I do not know. It WOULD, however, probably cover putting a concealed camera in your bedroom at home to secretly record your partner's activities there. Some states have laws explicitly covering that, some states would consider it stalking.
Tricky stuff, which is why I personally would research the law in my own jurisdiction before doing it.