Use control p5 to create buttons in processing and use them to control 7 segment or a servo connected to an arduino. Note that you need to change the port number according to the port assigned by the laptop to your arduino. The buttons in the servo file are used to move a servo at different angles. For the seven segment program I have added a mod logic to control the seven segment accordingly if the button is pressed second time. For it to run upload the arduino code on the board and simultaneously run the processing file.
Pin numbers:
Servo - 7
7 segment(in alphabetical order)refer the image
2,3,4,5,6,7,8,9