I was just looking for a similar answer. I have Debian 9 and currently have Nvidia driver 418.34 successfully installed along with CUDA 10.0 tool kit
I would first start by asking what your current GPU is? You need to make sure that your current GPU is compatible with Nvidia driver 410 (or 418.34). I also know that the two drivers (384 and 410) will not coexist together at the same time.
I recently got an RTX 2080, and Nvidia recently released the newest version of their driver (418.43). I went to the Nvidia website and downloaded their ".run" file for v418.43. I then removed the old driver (v384) using aptitude. Afterwards I tried to install the new version with the ".run" file, but it kept saying I couldn't install because I was currently using Xorg.
Try installing it by Alt + Ctrl + F2 and running the ".run" there. Try to install the new driver without rebooting.
If you reboot, you might not be able to boot after, but I have a possible solution to this if you are interested.
Once the driver was installed, you can test by running "nvidia-smi" in your terminal.
I then went to Nvidia's website to download the CUDA 10.0 ".run" file (I downloaded the one for Ubuntu 18.04).
At first the installer was saying that my configuration was not compatible and if I wanted to continue anyways. I said "yes".
I also said "Yes" to install the tool kit and the samples, but refused the nvidia driver install.
The installation finished as "incomplete", however I went to the directory it was installed in and tested it with a test cuda program and everything work perfectly.
I will continue to do testing, but as of now everything seems to work as it should.
If you run into issues with booting or GUI not loading, I might be able to help because I ran into those issues.
I hope this helps. There is very little information out there for Debian 9 and CUDA 10.