What's the actual pay date for your check? I'm paid every other Friday, and my employer's payroll system will show my pay stub a day or two before that, it usually shows up as a "pending" transaction at my bank on Thursday, and doesn't actually get added to my account balance until Friday. Sometimes that "pending" state is skipped and the transaction just pops up completed on Friday.

I haven't used Capital One, but it's possible they received the transaction this morning, but are just being slow to update your account. I'd give it at least a day before starting to worry, these things might be getting batched up into one in the morning (for anything received overnight) and one in the evening (for stuff received after the morning batch was processed). Could just be a timing thing.

Is this your first paycheck at a new job? That can sometimes involve extra validation (employer making sure you gave them a valid account), which can slow things down. That usually smooths out for future deposits.