Simple high-side current change to digital output
You should determine what voltage is on your outputs in either state and compare it with input voltage levels given in datasheet on your MCU. I suppose it is about 4 V at pressed state which is HIGH for 5 V TTL and CMOS circuits.

You have use amplifier for these signals. There are some choices.


Comparator. It need to have rail-to-rail inputs or higher supply voltages
PNP transistor (if voltage drop on R1 and R2 exceed Vbe ~ 600 mV) or P-MOS transitor with low enough threshold voltage.