My notes have been deleted from my iPhone

I didn't even delete the notes (not that I know of) last night I wrote three notes and this morning I went to go back and they wasn't there. No one knows my password. Can somebody else hack into my iPhone with out me even knowing? Why would they delete my notes-all it was was fitness routines- help me.

Do you by chance have a Mac laptop, desk top or iPad that may be synced up with your iPhone?