Is there any option to let a moderator know that an email account or OpenID is hacked and the person is doing things like abusing or breaking rules?
In such an event, what options does the genuine user have?
As has been noted in the comments, you should send an email to email@example.com as quickly as possible, including as much information about your account as you're able to.
Naturally it'll be a bit difficult for us to confirm ownership if you've lost access to the email account you registered with. However, if you're able to give us some reasonable suspicion that you're the owner, we can quickly disable all access to the account and then work with you to confirm your identity and then regain access under a fresh set of credentials.
Obviously you should also try to regain access to your email if possible, as well as take care of changing credentials on banking and other accounts that might be using your email for verification.