Millisecond Stop Watch

I am hoping this isn’t too hard but I am having trouble with a simple get time function. I need to have the code to get and display the current time in a textbox, but also be able to control the time with a start and stop button. When i Push the start button i need to have an overlay appear to log the start time with some info from other text boxes while the timer keeps going and then the stop button logs the end time. Any help would be appreciated. Thanks!!!