VPS is entirely separate from other servers with its own operating system and resources. Since you are the only one using that server, no one can access your files or mess around with your website in any way. With VPS hosting with cPanel, you are the only person who has a root password and can easily access the server. In most cases, even the hosting company won’t have your password and, therefore, won’t be able to enter. That being said, the company can gain access physically in an emergency, but that rarely happens.