But how do those hacks get into your phone? And how do they work actually? I have fairly limited experience with mobile development, but all I know doesn't give me confidence in the idea that you can do shit like that
Zero-day exploits in apps like WhatsApp and the phones OS. Recieving and reading a message that has malicious code attached can compromised a device. Even iPhones have been vulnerable. These exploits are valuable and temporary though, so get used on high value targets.