Door?

Soo I have two toddlers. We live in a mobile home And something that concerns me is the front door especially because our home is located it towards the entrance of the park. Is there anything or some type of security I can put for protection of my kids. Idk I’m scared they might open the door and just walk out or something. Maybe something that would make noise when someone opens the door? Something that can alert me. We are getting cameras. But the other thing is an extra thing for me. Just anxiety I guess & or scared they can get run over. Thanks I would appreciate it