Kali is a great tool for testing the security of your network and the operating system works on just about everything that can run Linux. That includes the Raspberry Pi. What's even better is a new distribution that brings along support for a touchscreen.
The special distribution is built for 2.8 touch screens. This means you'll find a special GUI interface built for touch and the small screen. It's likely a little clunky and hard to use, but the pocket-sized nature of it means you can keep it around without wasting a lot of space. Head over to Offensive Security to grab a copy of the distribution.
Kali with Raspberry Pi TFT Support [Offensive Security]