House mice are highly familial creatures. Their children cannot be raised with only one parent and they are not fit at birth to wander on their own. Mice live in villages, not families, and interact with each other en masse. If you have a mouse in your home that you have found that is one of the hundreds. So do not assume you ever have a single mouse in your home because one mouse means an infestation. Mice are very adept and getting into human homes. They are capable of entering weep vents which are very thin and hard for any other animal to access. They are also prone to entering broken foundations and getting into basements. Mouse infestations have gotten worse over time mostly due to global warming. As the temperature goes up in the summer to radical levels all wildlife will try to seek out a safe place to ride it out. In the case of mice that are inside your home. And you have no idea how desperate they are. They are hard to find and normally the only mouse you will ever see will be a young baby mouse that wandered away from the nest. This mouse will not be afraid of you and will seem like a mouse just wandering into your home. That is not how it works.
If you have a mouse infestation you can deal with it in one of two ways. The affordable domestic process will take much longer or the professional commercial grade treatment which will work faster but may be more expensive. One thing to remember is domestic-grade poison and traps are not as strong or as potent as commercial-grade poison and traps. So getting it done professionally may save you money in the long run.
If you want to try your hand at then make sure to buy the best domestic grade rodent bait you can find. Domestic rodenticide is the best and makes sure to put them in tamper-proof bait stations that lock, especially if you have children or pets In the house. Never put open poison outside as every animal in the area will go after it. Always put it in a bait station so the specific animal or rodent can access it. Rember wildlife is protected in Ontario, killing one with poison will come with a large fine. So if you are worried call a professional, they know what they are doing and will get rid of your rodent problem much faster.