How to create dashed lines in Photoshop

Round Brush = Dot

Select brush > Open brush panel > select basic round brush > adjust Spacing & Size > Ready to draw

Square Brush = Dashed
First, need to bring up square brush.
Select brush > right click to open a panel > click triangle > choose Square Brushes > select Append > 

(from here same as round brush)
Open brush panel > select square brush > adjust Roundness, Spacing & Size > Ready to draw