If I would see a mouse in my house, you can be sure that there would be more further away. Basically mice behave as a population moving from the most infested are toward the area where there is less competition, in other word no established mice infestation yet.
If you see 1 mouse? Can there only be one mouse in your house? Or is it the tip of the iceberg? In any case the easiest way to catch a mouse in your house would be to corner it in an area where is has no escaping. Regardless, the house mouse that was spotted manage to get in your home, so since there is a way, it is but a matter of time before another one find it as well.
The first thing that our clients normally do, is to rush on internet and look for a mice exterminator. However, it is almost as important to consider if the mice infestation is also affecting the neighbouring property. If you would live on an upper floor, it is obvious that the house mice would come from the floor below. After all mice do not fly.
So when we carry out the initial pest control mice treatment, we often advise the tenants to approach the neighbours living below and also sideways. In order to ensure the neighbours do not feel offended, the best approach is to tell them that you have a mice infestation, that the pest control company told you to let the neighbours know. If any neighbour react badly, it becomes easy to back off, telling that you mean no offence and barely do what the mice exterminator told you to do.
Also in most cases the neighbours would simply say that they have not seen any mice droppings or sightings. But what really matter is for the neighbours to actually check under their kitchen units for the presence of mice droppings. If there is any, they have mice, then they should seriously consider contracting professional pest control services in London.
The best way to get rid of mice in the long term is to carry out pest control mice program involving the property surrounding your home, so they act as a layer of protection, a little bit like a buffer zone. Otherwise, if you cannot kill mice before they reach you, you will have no other alternative than stoping them from reaching you with the mouse proofing of your home. If I found a mouse in my house, I would need to take action to stop more mice from ruching me again in the future.