2008 Toyota Corolla car diagonstic apps

Is it harmful to use a car diagistic apps since after downloading a free apps it said it might cause accident or death if I use the application or tge smartphones while operating the car? But how can I use the apps without opetating car, i.E - I have to start the engine to link car with tge apps?

I noticed my car was completely okay wen I left home in tge morning by it, after reaching home in the evening my driver said that my car ac makes noise when in use and sometimes the car itself when running, may be the belt got torn or faced other problem. However my query is can it be happened within a couple of hours or someone broje it purposely? How to detect?