If you're talking about using Osmand......

You can add viapoints in CT, write a note (such as distance) then download the GPS file, open it in Osmand (as usual) and wherever you have added a viapoint with a note there will be a red/white star. Clicking on this will reveal the note.

Alternatively, simply plot a route on Osmand as close as possible to the CT route and this will show distance (and elevation) to your destination.

It may be worth investigating on your Garmin unit too. My Wahoo will tell me remaining mileage and climbing at a touch of a button. Very useful at times, at others soul destroying :-)

Of course, this all depends on the length of route and the number of options for alternative routes.  For longer, multi-day routes the option of "trimming" the CT route (delete before or after waypoints) can be very useful for putting shorter sections into Osmand. 

Personally, I prefer the elevation detail in Osmand (distance by gradient) and often recreate the CT route in Osmand to see better what I'm letting myself in for. 

Thanks! I will try it. 

Thanks! I will try it.