Stop mind from thinking on other things while listening or learning

Anybody experience this while learning something or talking, listening, mind wanders suddenly to irrelevant things is this behavior normal to everybody basically I will not be in the present moment is this a symptom of ADHD I'm suffering a lot because of this I used to get bad reputation in the corporate companies because whenever getting the requirement I was suppose to listen properly and implement the thing as I'm a developer but I used to end up with understanding different things and this happened many times and also I'm an introvert and shy because of this trait I will not open up with my team members so that many things were unclear when they asked me "Are you clear with this?" out of fear I used to tell them that "Yes I understood" instantly and when I come back to my chair I used to assume things and implement which was leading to conflict and escalations. My fear was that when they asked me did I understand the requirement what if I tell them that I didn't understand and what they might think about me will they think I'm stupid to understand anything, dumb, useless. Did Anybody faced this kind of difficulty and how you overcame it..