You can show the value of a dial in a gauge chart in two different ways. First, you can use valuebox which will display the value of each dial next to the dial. Some padding adjustments can be made to move the value to a place most desired.
Here is an example of valueboxes being used to display the value of a dial:
The issue with using valuebox with gauge charts is that with certain chart dimensions the dials can cover the valuebox making the readability problematic.
Here is an example of valueboxes and gauge chart readability issue:
There is a different method to display the values which does not have the readability issue. The second method would be to display the values inside the legend as such: