My now almost 6 year old boy didn’t like pencils, crayons or the like either at that age. We just let him be. He was too busy exploring, running, finding insects, etc to sit and do anything.
He will be 6 next month. Sometime near the beginning of this school year, he decided that writing was neat and started doing it. He copies words off of books and magazines, tries to spell things himself, colors, etc. He is actually now moving faster than all my other kids did at this age in learning to write and read.
So at 4, I wouldn’t worry about it. Give him other sensory experiences that will help with the writing task later. Painting, shaving cream writing/drawing andplaydough/clay are good for find motor. Gross motor skills will help support fine motor later so anything that works his back, shoulders or arms (ie throwing balls, building with things, etc) would help also.
God has a timeline worked out for your sons development already. No need to rush or worry. It will happen when it happens!
-Rebecca