Voice recorder that won't raise suspicion if found ?

[hoochymamma]

For example usb voice recorder, you can just hide the file and unless you have "show hidden files" enabled in your pc you won't be able to tell anything is being recorded.

I am looking for something similar, but with a device that will be small enough to hide in really small spaces for a lengthy duration of time (around 1 week).

It doesn't have to have a battery capacity of 1 week of course, but it might need to stay hidden for 1 week before I will be able to retrieve it.