Any internet-based device can be hacked. A goal is to make it hard for someone to gain access to your VPS. You have already taken the first steps by configuring a firewall (UFW) and enabling Fail2Ban.
There are several other methods that you can use to add security to your VPS with little effort. This lab gives you an overview of these methods.
Here is a shortlist of security methods that you can implement quickly to provide a wide range of protection.
Configure a firewall
Harden SSH logins
Use a non-default port
Login using a non-privileged user
Restrict root access without a private key
Perform automatic updates
Securing a VPS from OVH
How to Harden your Ubuntu 18.04 Server from HostAdvice
How to Secure Your Server from Linode
5 Steps to Harden SSH Server on Ubuntu from LinuxBabe