Background check?

Where do you go to get a background check on someone you are dating... This is my first relationship in 9 yrs. I feel like he's the one but also feel like he's hiding something...I'm not sure if it's just in my head or just feelings from my last relationship since it ended so badly or if there's some truth to how I feel? I'm a single mom and not sure I'm ready for him to meet my daughter until I figure him out...