Advice to monitor Ranco Temp Controller or furnace temp

I’m using a temp controller similar to this Ranco model to monitor the temperature of water coming from our Heat Mor outdoor wood boiler: ETC Supply. Ranco ETC-111100-000 Digital Temperature Controller:0-10V Output. Basically if the water coming in is greater than 110 F, the controller shuts off the outdoor unit, and we are heating the house with the fan of the indoor unit and the hot water from the wood boiler. I’d like to add something to HA so that we know if the house is being heated by the Heat Mor or the electrical system so that we know if we can crank it up as desired. We’re trying to avoid having to go into the basement utility room to check. Additionally, it would give us an idea if the fire has burned out and we need to get outside to tend to it. Any suggestions for hardware that can either send the Ranco’s signal to HA or just a separate temp probe that can independently measure the temp in the duct and send it to HA?

I think this picture gives a better idea of how the system works: The controller measures the temp where the water enters the radiator at the top of the furnace, and if it’s high enough the outside unit is disabled: