There are professionals who have the skills and equipment needed to test a home for mold contamination, but homeowners can do preliminary tests for mold very easily.
Visual Inspection
Visual inspection of your home is by far the easiest way of testing for mold in your home. Don't just look for something fuzzy and green, though. Although mold commonly looks like this, it also can be slimy, and it can be white, brown, black, yellow or even pink. Look for molds in places that are damp, dark and warm, since most mold species thrive in these conditions. Areas like this in the home can include crawl spaces, bathrooms and basements.
Swab Test
If you don't see mold, this doesn't mean that spores aren't present--it just means that the spores haven't created colonies that can be seen with the naked eye. You can confirm mold's presence with a cotton swab test. To do this, take a moist cotton swab and swab the surface of an area you want to test. Place the swab in a sealed plastic bag with anything organic, such as a piece of fruit. The fruit will serve as a food for the mold if it is present. Put the bag on top of the fridge where it is warm and wait a day or two. If mold grows on the fruit spores are present in the tested area.
Smell
Use your nose to detect where mold might be. Mold usually smells musty, like dirt combined with rotten material. If an area of your home smells like this, mold is probably present. Try to avoid going into that area of the home as much as you can until you can treat the mold properly. Don't try to sniff actively, since inhaling mold spores can make you sick. Just be aware of what mold smells like and walk through your house to see if the smell is present.
Taping
If you see something you think is mold you can take a sample with clear adhesive tape. Pull off enough tape to fold over and form a tab you can hold. Then pull out a few inches of tape, press the adhesive side gently against the mold using a Q-tip, and then stick the tape, mold side down, onto the outside of a plastic bag. Fold that bag in half so the tape is covered, then seal that bag in another. This process may seem a little complex, but sticking the tape to the outside of the first bag makes it easier for a technician to remove the sample without disturbing the spores; this makes it safer for the technician and keeps the sample intact for visual analysis. The second bag ensures that there is added protection against the spread of the mold spores should the first bag rip or tear. You can send this sample to a laboratory to have it analyzed without having specialists do a home inspection.