Long story short, I need to create an application that monitor the sound volume on a computer. The computer\'s user must not be able to stop the application no matter what.
I'm not accusing you of malware - just wanted to illustrate how bad it would be if you could easily make a program that the user can "never stop".
But from what I gathered....
Sounds like you want to make it a service. https://msdn.microsoft.com/en-us/library/d56de412(v=vs.110).aspx.
Another (easier I think) option is just to make a console app that starts up from the Task Scheduler http://www.c-sharpcorner.com/uploadfile/manas1/console-application-using-windows-scheduler/.