Wait, are you trying to spy on your boyfriend or husband? Why do you want to know the best spyware program? I'm not going to fall for this trick.
Google "cell phone spyware" and you'll find various questionable sites that want to sell you "amazing" spyware for your phone. They claim to be able to catch cheating spouses. Don't buy it, both because it's probably a rip off and also because tapping someone's phone is technically illegal.
Can someone hack your phone and listen to your calls? Sure. People can hack all kinds of stuff if they want to. But does anybody want to? Doubtful. Can your cell be hacked and your private information stolen? Sure. Of course. Password protect everything. Change your password. Keep your info safe. That Web browser on your phone can pick up spyware. Cell viruses aren't as common as computer viruses, but they happen. Run free anti-spyware software programs. Take your phone to a store if you think it's been compromised. And don't spy on anyone.
and don't spy on anyone. don't forget, and don't spy on anyone. karma's a boomerang. so don't spy on anyone.