I guess that depends on how sophisticated your hacking is and how sophisticated the bank's auditing systems are.
If you just updated your bank balance, the bank should catch that very quickly, because their books won't balance. They'll have a credit with no matching debit.
If you're smart enough to update both sides of the ledger, the bank will still surely notice something when they try to reconcile. Where did the money for this deposit come from. If you enter that it was made with cash, then when the bank does their cash reconciliation they'll find they have less cash than they should. If you say it was a direct deposit, they'll turn up short on deposits received. Etc.
If their audit trail is sophisticated enough -- and bank audit trails tend to be very sophisticated -- they'll track it back to your account pretty quickly.
There was a scam that was discussed a lot about 20 years ago -- I don't know how many people really got away with it, but it was a big buzz in computer circles -- that a programmer would change the bank's interest calculations to round fractions of a penny down instead of rounding of to the nearest whole penny, and then put those pennies in a dummy account created by the programmer. Few customers would notice that there interest was a penny short, and if they did, they'd grumble, "Hey, the bank is rounding 14.9 cents down to 14 instead of up to 15, what a rip-off", and then forget about it. Who's going to make a stink about a penny? Meanwhile if the bank has a lot of customers, the programmer is collecting significant money off all these pennies. And the bank's books would balance: if they're paying, say, 2% interest, 2% of the total of all count balances matches the total interest paid. They'd have to look pretty close to see that one account got way more interest than it should while many other accounts were a penny short.
The point is, you need to have the money come from someplace or somebody's books won't balance. You can't just create money out of thin air and expect no one to notice.