Can you give an example of what you are planning to have?
In Canvas, there are a number of ways you can go about it depending on what is it that you are looking for. Here are the two examples that should help give an idea:
The onUpdate() function, when passed can give you the reference when the user updates the values:
Another one is by exposing your own custom context menu:
Which will give you the reference to the cube and elements to the function you will assign into it. For the above example which you will find under samples application --> DBR, clicking the custom context menu provides this information (note that the data is provided into the function; the prompt is all in the custom function you will provide):