Like using CyberGhost with a proxy it is also possible to use CyberGhost and TOR at the same time. In that case your traffic will be routed through the CyberGhost network as well as through the TOR network (CyberGhost on port 443, TOR on port 9001 or 9050/9051). The TOR entry will just see your CyberGhost IP.
Is it necessary? Not really, since the CyberGhost encryption of 256 bit AES is not (yet) breakable, but it might be a possibility for people who want to MAKE SURE.
If you want to use CyberGhost and TOR at the same time, please start CyberGhost first, log in to an anonymization server and then start your TOR browser.
Note: TOR itself as well as the doubled encryption work will slow down your Internet experience noticeable.