You should be able to tell if your dog has a fever by feeling their head or other parts of the body.
That won't tell you the temperature but you could probably use an infrared thermometer and point the infrared thermometer at the dog and find out the dogs temperature.
A dogs normal body temperature should be from 101 F to `102 F which is normal for a dogs body where'as a human would be having a fever if they had a temperature of 101 F.
A dogs body will be warmer than a humans and that's normal any temperature on a dog above 102 F is likely a fever and if it doesn't go down you should take the dog to a vet.