look at my "ProMicro_ExtensionBoard". I use it for "Saitek x35/36". Here two mcp3208.




and special for you only promicro + mcp3208.




pins:
mcp3208.VDD = promicro.VCC
mcp3208.VREF = promicro.VCC
mcp3208.AGND = promicro.GND
mcp3208.DGND = promicro.GND
mcp3208.CLK = promicro.SCK (also "SCK" possible to share with button matrix, you can use this pin for SPI and for buttons)
mcp3208.Dout = promicro.MISO (also "MISO" possible to share with button matrix, you can use this pin for SPI and for buttons)
mcp3208.Din = promicro.MOSI (also "MOSI" possible to share with button matrix, you can use this pin for SPI and for buttons)
mcp3208.CS = any pin of promicro (this pin must used only for SPI, and it pin must be assigned at JoySetup)

and last note, if you like to use SPI and button matrix together all 3 SPI pins(MOSI/MISO/SCK) must be at one side raws or colunms. At my sample "ProMicro_ExtensionBoard" SPI shared with raws.

and connecting pot or hall to mcp3208 pins CH0-CH7, as regular ADC Pow(vcc) Gnd and out.