There are hobby projects which allow connecting an IoT device to a blockchain. The device has to include a Dapp software and connect to a node of a blockchain.
In general for almost every operation on the blockchain that the Dapp places the user of the Dapp has to pay for it.
So an IoT device connected to a blockchain will be creating traffic and payments for the blockchain.
For more on what a Dapp really is please check this article -
What a Dapp really is
