If you can do this in your scenario needs thorough analysis and depends highly on your use cases.
Broker/Um and Kafka have been originally developed for different use cases.
Broker/UM are developed mainly for mom (message oriented middleware) use cases, especially guaranteed delivery.
Kafka is developed to provide data streams for streaming analytics.
There are some overlaps, but quite often it does not make sense to replace one with the other but rather use both for different use cases.