Firstly, even though it is true that some people are terrible at conducting interviews, don't assume that they are ignoring you and working on their laptop. Many interviews in large organisations today are conducted by a manager, untrained in interview technique, but conducted to a set of rules imposed upon them by a human resource department. As such, interviews can be a point-scoring exercise. The interviewer may actually be taking detailed notes of what you are saying, so rather than ignoring you, they are trying to listen. Later on, they may use what they have written about your answers to "score" you. In some cases it literally is the highest scoring candidate that wins; other times they may consider other factors too but use the scores to justify their decision, at least in part. This is based on my own experience working in two different government organisations in the UK as a manager who interviewed and hired.
It can be easy to be negative about some interviews and assume that you are not doing very well because of the way the interviewer is responding, or not. But if you want to get a job, keep positive! Remember that some interviewers can be as nervous about the process as the interviewees, and this can account for some behaviour. Also, if they are taking notes to "score" you, you must continue your interview with a positive manner otherwise your score won't be so high. In fact, if you think that they are making notes, my advice is to say as much as you can. Don't waffle, but say for example they ask for a list of things you have done. Don't just give a couple of examples if you feel you can list them all in a reasonable time. In score-based interviews, you can't really score less for talking more.
It would probably be inadvisable to try and say something to a prospective employer that could come across as rude, like checking if they are actually listening to you or not. But at most interviews you are given an opportunity to ask them some questions. Always have some good questions prepared that show you have done some specific research about their organisation. This also is an opportunity to show them that you are interested in them (not just in getting any old job), and should also be a chance for you to interact with them properly. If they are still muttering a few words to you whilst typing at this stage of an interiew, then perhaps you are right, and they are just rude. Personally, I wouldn't want to work for someone like that and I'd consider it a lucky escape to not get that job. But always be polite, because you never know how this employer might be connected to other prospective employers.