Need little help from hosting pros

So i never used VPS server for hosting before, My new site is on VPS. I am using cloudflar. The thing i dont want to expose my host, but some bot was able to find my server ip and how the hell that happen

http://prntscr.com/l37fa9

Some one can explain whats the issue here and how they can visit my server ip?

Maybe your current IP address had been using by someone earlier.

Kind of simple. The amount of ip‘s are restricted. Bots crawl whatever they can find. I had an honey pot open on a residential IP and an open MongoDB to see how long it takes. Less then 24h someone deleted the dummy content of the database in exchange of a bitcoin number and I should pay if I want my data back.
So there are people who check for usual Ports (eg 80 / 443 Webserver, FTP, SSH, Databases) and IPs. So whether your host was known before or not doesn‘t matter at all. You will be scanned.
Latest point when you set up your site a simple dns trace will show the link between the url.tld and the IP.
You will need to take precautions to secure your VPS or at least to backup it on a regular base.