Is it possible to get a graph of the cloudheight with meteohub?
You mean like this graph?:
https://www.tceweather.com/cloudbase_graph.html although it has X-axis as time and Y-axis as height.
You should set up a Meteohub virtual sensor to generate input data for a graph. See this how-to explanation:
https://forum.meteohub.de/viewtopic.php?f=9&t=14621 . It describes plottable cloud base heights calculated by a virtual sensor.
BTW, thanks for this idea of cloud height graphs out of the Meteohub.
Edit: The cloud base height over time looks a lot like the Chandler Burning Index when graphed (except when the cloud height is above about 10k ft, the CBI hits the 100 cap and then flatlines over time). Both use T and RH (indirectly for cloud base), so that would be expected.