Updated (Kinda) Probe Guide
This is for the 9 probes in the overworld that will be destroyed if you do not collect them, not the remaining 10 probes that are required to be collected as part of the optional final level.
Farm:
Upon first spawning, head to the bush with scorch marks around it to the left, interact with it to find the first probe.
Bottom Right Corner of the map, head down the path to get the next probe
Final Probe is located in an open crate near the stalls to the right of the well
City:
First Red Trashcan upon entering the city, near the fountain (Same probe spot as before the update)
Behind the church in the upper right corner of the map, while you're here head to the large barricaded hole to the left to get the next probe
Upper left area of the map, right above the casino, interact with the manhole near the tires and flipped car to get the biohazard key, use this to enter the area right below the barricaded hole that you found a probe in it.
One probe upon entering the biohazard building
First room upon jumping down the hole: One probe, you won't be able to get it from here so keep moving until you get to the second room.
Second Room: Keep going Left until you reach the path that leads down, head that way
(While on that path, Go to the second right path to pick up documents/clues #2)
Keep heading down until you reach two paths to go, head left to enter the third room, head right to follow a path that will allow you to get the probe that was in the first room.
Third Room: The final probe for this location is right in the center, collect it then head left to exit the the stinky sewers
My guess is that there's one clue for each main map, farm, city, Govt. Base, etc, however I cannot figure out just where the clue on the farm is, I'm almost positive it has to do with the fire pit behind the house with a car in front of it however, since it was recently added with this recent update, just have no idea how it would be possible to trigger it to get the clue or if it's just a tease for future content