聲卡要怎樣才能接話筒?

well, if you talking about regular usage from phone, you need a telephony board
with the digital phone connection to telephony board, those are professional solution ...
Click on the link below to get an idea what kind of similar hardware you need
http://www.nch.com.au/vrs/acc/index.html
I don't recommend DIY, since the quality can be bad...