A cheap $10 digital temp will do fine... Check accuracy with boiling water. Need two though (one for th meat and one for the pit).
DO NOT poke around the different spots. Insert the probe into the meat and leave it there for the duration of the cook. Set the pit probe near but not touching the meat. Control the pit to ~220*F and take the meat off ~195*F, leave the probe in, wrap it in foil and towels and throw it in a cooler (to keep warm). The collagen should continue to break down. Take out of the cooler and pull/shred when ready to eat.
Plan to be done at least 2~3 hrs before you're ready to serve. You can keep the meat hot in the cooler for hours but can starve waiting for the meat in the smoker to cook.
With ribs, just allow for 6hrs (spare) or 5 hrs (babybacks). No probe on the meat needed.
195 internal meat temp is WAY TOO HIGH...
Smoke at 200 to 225 degrees F until internal pork temperature reaches 160 -165 degrees F . There will be carryover cooking.
Wrap finished meat in foil to rest at least 20m to allow the meat to rest and redistribute the juices; but do not use towels or paper or anything that can soak up liquids around the meat itself.
You will also find better results using a larger butt, say 7lbs or so and performing an overnight brine process.