1. Solder the low-pass filter on the 4×6 com universal board by referring to the following circuit diagram.

2. Connect the "Signal Input" on the low-pass filter with D6 on UNO; wire the filter and UNO to the common ground.

3. Plug the digital button into A1 on UNO. As shown below:

4. Plug the audio jack of the USB mini speaker into the audio port of the output end of the filter.

After the above steps are completed, power up the UNO and download the
codes into it, press the digital button and then you will hear the sound from the USB speaker.

Source page: pcbway