Harry wants to know if his smartphone can be hacked and would he know if it was? Leo says yes, and no. Smartphone operating systems are very sophisticated, but Android is more open source and, as such, could be more vulnerable. If anything, your smartphone knows where you are at all times, and as such, so does your phone company. And police can get that data by a simple request.
But unless you're a celebrity, a politician, or a member of a "three-letter agency," it's extremely unlikely you'll get hacked. Just don't download suspicious apps from questionable sources.