Add a $25 camera to have an old Raspberry Pi working as a surveillance camera using free motionEyeOS
Although Zoneminder will run on a Raspberry Pi it really does not handle 6 or 8 higher res cameras very well. Sometimes though you just need a short-term solution for a business theft problem, or something, in particular, you need to watch over, and many of us have a Raspberry Pi 1 or 2 sitting around which we have replaced already with a newer mod
With just the addition of a camera (either the 8 megapixel Pi camera itself, or any other supported USB camera), you can install motionEyeOS on that Raspberry Pi and turn it into a pretty good surveillance camera which you can log into via a web browser.
The post at http://bit.ly/2CXZUV0 gives a good tutorial on exactly how to do this (including the fitting of the camera). MotionEyeOS will also upload media files to cloud storage services likeGoogle Drive and Dropbox, and some have also connected it successfully to Home Assistant home automation dashboards.
