Are there any good security cameras to install in cab?

I'm a Company driver who's been driving for about a year now. Up until now I haven't really had any incidents but recently I was on my home time and when I came back to the truck someone else had clearly been inside. Luckily they didn't take anything, but my belongings had been moved around, seat and steering wheel adjusted, etc. I was wondering if there are any good security camera systems I could install for when I'm away from the truck in case something like this happens again.

 

Did you leave the truck at a company yard or a truck stop?

 

Look on ebay for nanny cams. They are small and very hard to notice if placed out of line of sight