You can use the method getPageLabel.
I found the code that extracts the page labels, however I am not sure how to write the results to a .csv file, not the console. Also, is there a way to add a menu item with the script?
Listed the code here:
var labels = this.getPageLabel(0);
for (var i=1; i<this.numPages; i++)
labels += ", " + this.getPageLabel(i);
In Acrobat you can create a Report document and export it as Excel file.