I used https://github.com/StAlphonsos/scriptologie/blob/develop/scripts/tomboy2org.pl which is mentioned in http://orgmode.org/worg/org-tools/.

Here is how to proceed. (Note, however, that you may want to clean out your notes before so that you do not migrate unwanted notes.)

1. Install the dependencies for running the script:

   
   
   

   sudo apt-get install libxml-twig-perl libtext-format-perl
   
   




2. Download the script from https://github.com/StAlphonsos/scriptologie/blob/develop/scripts/tomboy2org.pl.




3. Close Gnote so that any changes is written to its database.




4. Run the script. I chose to run the script with the option -notebooks to make one .org file out of each Gnote notebook:

   
   
   

   perl tomboy2org.pl -notebooks -verbose