Have you found termite damage IN your house? IE have you gone into your basement/crawlspace and seen termite damage? Or have you just seen termites in the areas around and outside your house? If the latter, you may not have a problem. Termites are all over underground and eating dead wood. It doesn't mean they are in your house.
My termite knowledge is basic so someone may correct me if I'm wrong on any of this.
Easiest way to check is to look for tunnels. Termites can not be exposed to open air; they love and need moisture at all times. Wood touching the ground is their favorite thing because the wood stays wet and they burrow up from the ground into the moist wood.
They will burrow through concrete but don't like to, and since concrete is typically what is in contact with the soil, they have to crawl along it, which they will only do in a mud-tunnel they construct, to get to the wood.
Check for mud tunnels along concrete foundation that lead along the foundation from the ground to the wood of your house. Search online to see what they look like. Check this outside and in your house too (Basement/crawl etc).
If you see what looks like damaged wood, it might be years old and from a past infestation. Hack at it with a flat-head screwdriver to break some small pieces of wood off. If the infestation is accurate, you should see some white termite nymphs (no wings).
If you don't find anything, the best treatment is bait stations. You can install these. They stay in the ground and you replace the baits as they are taken. The termites take the bait underground, back to their nest, and it slowly kills them and the queen. It's the standard preventitive way of dealing with them and it's pretty effective.
If you have an ACTIVE termite infestation, I'd advise you to call in a pro at that point. It gets a little more complicated here as you have to know exactly where they are entering the house, and treat with a special long-lasting chemical at just the right depth. I guess it's possible that you could buy this and treat it on your own but I have no experience with that and can't speak to it.
If you try sprays that kill them when they cross a boundary, it won't kill the queen so the colony will just keep living and sending more termites out. If they are already in your house, the bait stations might not work because the colony that found its way into your house may likely bypass any bait stations and keep going straight for the house. This is why I suggest the pro when it gets to this point.