Hi,
You can use Azure Functions with Azure Event Hubs trigger and Cosmos DB output binding to move data from event hub to Cosmos DB.
Azure Event Hubs trigger for Azure Functions
https://learn.microsoft.com/en-us/azure/azure-functions/functions-bindings-event-hubs-trigger
Azure Cosmos DB output binding for Azure Functions 2.x and higher
https://learn.microsoft.com/en-us/azure/azure-functions/functions-bindings-cosmosdb-v2-output
Please click Accept Answer if the above was helpful.
Thanks.
-TP