If you have a smart phone, yes the mic will be built in. If you got your phone new, it should have also come with a headset which would probably have a mic in it, as well. If you don't have a headset, you can get those fairly cheaply at any office supply store and even some dollar stores.
I'm not sure what to say about your marriage situation. If you have voiced your concerns to your husband and he rejects what you have to say, then keep praying. Only the Holy Spirit can convict him. It may be that as he sees changes in you, that he will eventually come around.
I don't necessarily see his views on remarriage to be a problem, though. It's not a critical salvation doctrine and hopefully, the issue will never have any relevance to either one of you. If there are other doctrinal issues that you disagree on, ask him to share Scripture references supporting his position and you do the same.
I would be more concerned with the recurring sin and the people he is hanging around that may be encouraging that behaviour. Again, though, although you can voice your concerns to him, only the Holy Spirit can convict him. If he is truly seeking after God, he will come around in his own time. Work on yourself as much as possible and keep praying for your husband.