It’s good to be aware of what your safety appliances can do. In this case, a carbon monoxide detector cannot detect propane.
If you want to detect propane in the house, you’ll need to install propane detectors throughout your home. Propane is odorless and difficult to notice on its own, but propane companies add a chemical called mercaptan to give it a distinct, unpleasant scent—this will help you detect a leak.
While propane is non-toxic, a propane leak can lead to a fire. If you suspect there is a propane leak, leave your home and reach out for help.