Connecting ipencil to iPad Pro with usb c

You must use the correct Apple Pencil. An iPad with USB-C requires a second generation Apple Pencil; the first generation Pencil is not compatible with 2018/2020 models of iPad Pro.

Here is the full compatibility list:

Apple Pencil (2nd generation)

You can use Apple Pencil (2nd generation) with these iPad models: 

• iPad Pro 12.9-inch (3rd generation) and later
• iPad Pro 11-inch (1st generation) and later

Apple Pencil (1st generation)

You can use Apple Pencil (1st generation) with these iPad models:

• iPad Pro 12.9-inch (1st or 2nd generation)
• iPad Pro 10.5-inch
• iPad Pro 9.7-inch
• iPad Air (3rd generation)
• iPad (7th generation)
• iPad (6th generation)
• iPad mini (5th generation)

Not sure which iPad you have? Identify your iPad model.

More info here:

Use Apple Pencil with your iPad or iPad Pro - Apple Support