is it easy to hack into a wi-fi single?

[Just Asking]

I finally moved to town, and after 2 months in a apartment, I have recently moved out of the apartment complex and into a house right across the alley (only place I could afford). Now I can get internet, but am concerned that the people in the apartments might try to hack into my wi-fi since they can not get the internet there.
For some reason, none of the local providers will provide there. Something about a prev tenant doing some illegal activity, so now the entire place is blacklisted.

Would it be possible for them to hack my account and got n without my knowing it?
If so, is there anything I do to prevent it?