Can I use custom subdomain?
And if can, how to update domain provider’s panel 
Please help!
Thanks in advanced!
Yes, I’m fairly sure you can. Just have the DNS point to that location
I believe this problem was solved on our discord by Andy Rak:
"For subdomain instead of @ in “Name” you type your sub domain
For instance you want sub.yourdomain.com
In your DNS provider you fill up the following:
Type : A,
Name : sub (basically the subdomain name - not @),
Content / Value : (the IP provided in DH domain settings),
Then in the custom domain field in your Divhunt domain settings, you type in the full url : sub.yourdomain.com and click update, then publish"