The answer to 'how did cockroach get in my house' is that cockroaches can enter your home through small cracks and crevices, come in with boxes or bags, or be brought in on secondhand furniture. They are attracted to food, moisture, and warmth, and can quickly multiply if left unchecked.
Cockroaches are common pests that can be difficult to get rid of once they have infested a home. They are drawn to sources of food and water, and can squeeze through tiny openings to gain access to your home. They may come in with deliveries, hide in boxes or bags, or be brought in on secondhand furniture. Once inside, cockroaches will quickly breed and spread throughout the home if not properly addressed.