Not from what i know, if by 'hacker' you mean a person, or a group it would be nearly impossible, they could even do what the people above said but if you just a normal person why someone would do that much effort to listen to your useless communications ? If you talk about a three letter gov agency then it may be possible to do that but not only using your phone signal, here it may be how they can do it:
1.Malware can installed in various ways, including fake software updates, emails with fake attachments, and security flaws in popular software. Sometimes the surveillance suite is installed after the target accepts installation of a fake update to commonly used software.
One example i'm aware of is FinFisher, also known as FinSpy.
2.Hacking to your PC and then install an spyware on your phone when you connect it via USB or maybe even by just being in the same wireless network.
3.Just force your phone provider like AT&T or Verizon to just hang out your data, some paranoid people even believe they already have backdoor installed on their system so the gov can just spy anyone without even talking to the phone provider or your ISP, this may be true or not.
Remember that even your apps and sites your visit on your phone can track you using cookies,browser fingerprint.(I recommend using Ghostery app browser for visiting sites)
Now here how to protect you against that:
1.Ignore all updates of programs you use, if you want to upgrade them do it only in their official websites using HTTPS if you can.
2.Never open attachments you receive by email, even if it looks like its from Google,or Windows
3.A security flaw in Apple's iTunes allowed unauthorized third parties to use iTunes online update procedures to install unauthorized programs, that seems to be patched but it's best to not let any app to auto-sync to your phone.
4.Only install apps from Google play store or from sources you can trust and NEVER let checked the option Unknown Fonts(may be look different on your device, mine is not in english so i'm doing a translate here)
5.Always check your apps permissions,if an notepad like app wants to send SMS or do calls then you should be very suspicious about it.
Is your phone rooted? Don't seems that way, but if you are really concerned i think you should root it because then you can harder android by that ways:
When you root, you usually install a superuser manager that prevents apps from gaining root access without you know, that may prevent someone from unloading something in your phone that can root it without you know and then your phone will be in their hands.