There are three approaches that you can utilize for using data from an app created using App Designer in a different function or script. All these methods are based on saving the data from the app to the MATLAB Workspace, which the other function or script can access.
1. Using "assignin" to assign the value of the desired variable in the workspace. You can refer to the following documentation link for an example:
You can use any of the above approaches inside of the "CloseRequestFcn" such that when the app is closed the variables will be saved as the "CloseRequestFcn" is executed. Here is an example of using the "CloseRequestFcn" for a figure :