If you need to reach into small holes or grooves you can use any one of the test indicator points which have either M1.4 or M1.7 threads, a 2 mm diameter shaft, a length of up to 5" and a small diameter carbide or ruby ball at the end. This is accomplished with an Adapt-A-Tip adapter. The adapter is about .33" long and it screws into any dial or digital indicator spindle which has a 4-48 thread. Then you screw the test indicator contact point into the adapter. It's an excellent solution for fitting into tight spots.
Adapt-A-Tip shown. The test indicator point is not included and is shown as an example of this adapter's use.
GIROD-TAST
The "other" Swiss indicator still made in Switzerland.