@Marcia102 Unless your rules explicitly state otherwise, people tend to take "no smoking" to mean "no smoking indoors." If what you actually mean is "no smoking anywhere on the property, including outdoor areas," I recommend saying that - perhaps even adding a helpful note about where the nearest place is that someone can use smoking/vaping products.
I wouldn't suggest directly posing your suspicions to the guest. But since you have a very new listing that hasn't been refined yet, what you can do is contact the guests to inform them that you've updated your House Rules in greater detail, and invite them to ask if they have any questions.
I find that asking one guest whether anyone in their group is a "smoker" is an exercise in futility. Plenty of people who smoke do not self-identify as smokers, and it's very common for former smokers to fall back on old habits when dealing with a new situation like staying in a stranger's house. I don't know if any of this is the case with these specific guests - sometimes a person just needs to get outside for a bit, even in cold weather. But if you approach a guest with the presumption that they've been dishonest, they'll immediately go on the defensive, and your fragile guest-host relationship is unlikely to recover from the fallout. The best way to communicate here is to give them the benefit of the doubt and make it about your own duty to provide clarity.