The very scientific method is supposed to be only applied to the
physical world, just like an ordinary tool (hammer or screwdriver). I
don't know if you're aware of that but you're applying a strange
metaphysical interpretation upon science. You say science is the only
way to get knowledge and scientific method is applicable to metaphysics.
Nowhere in science there are such statements.
Well, I'm saying that science is the only way to get knowledge that is objective. (won't change depending on who seeks the knowledge) Thus making the scientific method, the only way, that I know of, for an individual to determine the accuracy of a claim. Additionally, I would argue your assertion that the scientific method can only be applied to the physical world is flawed. After all the scientific method is simply a question to which someone applies systematic observation, measurement, and experimentation and then formulates, tests, and modifies a hypothesis to that question. In principle, the scientific method can be applied to study things that aren't directly perceivable, energy for example. I will grant that the scientific method is better with some subjects than it is with other subjects, and there are some questions it can't answer, but anything that has an impact on the physical world can be measured, and directly or indirectly observed.
In fact you are following a philosophical system called positivism. Idk
if you're aware of that or if you don't know what the scientific method
is or what metaphysics is. Probably you're just a blind follower of
positivism (lately it's spreading like a plague).
I'm aware what positivism is, and I gladly support it because the "mission statement" of logical positivism is to prevent the confusion caused by unclear language and unverifiable claims, both of which are ideals I agree with completely.
The scientific method is a philosophical system and metaphysics is also.
Everything I said is subject to philosophical study since the dawn of
man. And the test of it is time. Nature itself "hates" waste. If
something is not true it will never last too much time. My view is
standing for thousands years throughout many civilizations. Your view is
just a little shadow in the stream of time. No matter how hard you try
you simply can't change this fact.
You are right, metaphysics is older than the scientific method, however, the scientific method in its relatively brief period of existence has provided a large body of useful, objective, and verifiable information. Making it, in my opinion, the more valuable "tool" for attaining knowledge on which to base my actions and beliefs. In the same way that a jet is superior for traveling long distances, as opposed to a unicycle.
Giving a more direct answer to your question I get my information
through philosophical inquiry and through metaphysical revelation (both
public and private) brought by non human beings (human souls can't do
that without special permission) and through the test of time/history.
So nothing that anyone else could double-check to make sure you aren't just delusional or suffering from a severe confirmation bias? Yeah, that seems like a great way to acquire knowledge that you can trust.