Scratch to micro:bit bridge

You can use the scratch to micro:bit bridge, developed by MrYslab:

https://github.com/MrYsLab/s2m


ScratchX MacOS extension

If you're using Mac OSX, you can install this plugin with the scratch device manager:

https://llk.github.io/microbit-extension/


Bluetooth

You can use the S2Bot App plug-in with Scratch, which allows any compatible BLE controller to interact directly with Scratch project:

http://www.picaxe.com/BBC-microbit/


Additional Information

 https://github.com/carlosperate/awesome-microbit/blob/master/README.md#scratch-extensions