Create a routine. To open Notes when a call is being received by anyone, or contacts. You can tailor it to how you want it. Sorry, didn't read the other user addressing this in time. 
You can create an app pair, and it will create a bubble as shown in photo 2. My note has instructions on how to do it.. not sure if that's what you are looking for, as the bubble pair I created can take a note when initiating a call. don't use my phone, so I was just testing Google voice. In the middle there's 3 dots that will appear on the line separating the apps and it will show a star. 
