You can use Atrium Integrator for this purpose.
You can create a Pentaho job using CMDBInput step plugin to extract data from CMDB and then use either
Database output plugin or Rest client step plugin if HP uCMDB has published REST APIs CRUD operation.
There is a specific integration job for uCMDB Data Flow Probe to query BMC Atrium and map the results on uCMDB Ci types to populate it.
I think it requires a license though.