hope this helps, but the best way is to just talk to your husband and ask him why he is doing this!
If you see signs that is coming home late, leaves extra early for work, he starts using cologne, etc…. that means is cheating. Buy a tracking gps for $300 and another $300 for subscription so you can track him 24 hours a day where his car is parked and where it has been. They are so small and it is easy to hide in his car. Have access to his cellular bill account on line and see all phone records. Buy a voice activated digital recorder and record all conversations he is having inside his car. Hire a detective for $200 to $500 an hour. Good luck