Finally I managed it
If you want, you can use this for your initial Post.
1. You have to download and install Voicemeeter and Virtual Cable. Set "Voicemeeter Input" device as default in your Windows Soundoptions. After that you can choose the Virtual "CABLE Input" as Output device in discord (or what ever you use as voicechat).
2. After that, start Voicemeeter and set your primary audiodevice as A1 in the upper right. In my case, it's my headset (Lautsprecher (Sound BlasterX G5)).
The yellow box shows the settings for your voicechat device. I selected A1, to hear that sound via Headset and selected B1, to say VM, play this sound via "Voicemeeter VAIO device" (blue box). This virtual device, also goes via A1 to my headset.
3. Set the settings in Action, as shown in those screenshots
important here is, that you untick the microphone. Otherwise you record it twice. One in your Mic-track and one in the Discord-track)
CABLE Input (Discord)
Voicemeeter Input (Gamesound)
Your microphone
4. Now the recording should look like this
I dont know, why the single audio track starts a bit earlier. It should look like:
Ok, so I'm not a native speaker and my english is not the best, maybe you can take my stuff and "translate" it, in an understandable way