BusyBox is a small, versatile tool that is perfect for all kinds of embedded systems and even for some desktop computers. The app combines tiny versions of many common UNIX utilities into a single small executable. The utility in BusyBox provides a complete environment for your system. It can be used with any terminal emulator and will work on any device with a compatible OS. You don't need to root your device. 
Installation

Step 1: Download and install BusyBox from Google Play.

Step 2: Run BusyBox, you will get an option to start as a service, run as a process, or start as a server.

Step 3: Run your app, you can use the app as a regular user.

Step 4: To run BusyBox as a service, you can stop the app and start it again.