Azure Function Trigger using Azure Relay Instead of Service Bus

I know its possible to create an Azure Service Bus trigger so that an Azure Function wakes up when there is a message on a service bus queue. Since Azure Relay is built using Service Bus, is there a tutorial on how I can instead create a trigger on an Azure Relay instead? How does the Service Bus listener work that is able to listen "outside" the function to be able to trigger. I don't want to reinvent Azure Relay using Service Bus.