The floor has to be flat or else you put stress and strain on the locking mechanism and it can break. What you're describing isn't a minor out of level issue. It's a remove the hardwood and existing subfloor, install blocking between the joists (potentially sister the joists also, depending on their spacing) and then install a new flat subfloor. Once that's taken care of, then you can install the flooring of your choice. What you CAN NOT do is to put the laminate down over the old hardwood that's sagging.

There is no sub floor...since it is so old, the wood was simply put on on top of the joists, it's the same at our current house. Can we use a leveling cement/product on the floor and then lay a new subfloor over that? The dips are not very deep/large.

Sorry, but you can't do much different than what livewire described.
Adding cement or a leveling product will just add weight to an already sagging problem.
If you don't correct the support structure of the floor you're going to always have a problem. That's just part of owning an old home.

If repairing the floor isn't in your budget, why not just refinish the hardwood you have and live with it for now?

When our laminate floor was laid, the installer used leveling compound in the spots that were low. Then he put a thin layer of underlayment down (it was blue and not attached to the laminate floor). If you think the "sags" are caused by the flooring/joists, maybe being too far apart or weak, you should probably talk to a structural engineer to give you some advice.

Sags between joists mean that the joists are undersized, or too far apart, especially by today's standards. The floorboards don't have enough support, and thus sag. You need to do as LWO says and fix the support problem first. Otherwise it's a waste of money putting anything on top of that. That goes for flooring, cabinets, countertops.....all of that is compromised by the insufficient support that your current floor joists are providing.

Update...partner looked in basement, he is more handy then me. Apparently the joists run perpendicular to the dips, as does the hardwood obviously. S these small dips are actually perpindicular to the joists. They are barely noticeable, not a very large dip, I never even realized it was there until recently. We laid some of our "test laminate" we purchased and there is only a problem with one of the "dips"...the rest lay sufficiently flat.

We can't just refinish the hardwood because the dogs will tear it up with their nails. A good laminate is our only option to keep our home looking decent.

Next time I go to house ill look more closely at what's going on and if it is just one area...just saw the one area and panicked!!!! If it is a systemic issue we will have a structural person pay a visit.

If it's out of level over 3/16th over 10', you'll void the warranty. Worse than "creaking", the floor itself will become damaged from the flexing. The tongue will crack. If you can't get the floor flat by rebuilding it, then don't bother with laminate. Maybe a snap together vinyl plank floor would work better. It's much more flexible and the floor doesn't have to be as flat.

Good luck with your project.