Raising Ducks?

I am interested in raising a Duck and know most of the basics and just want to know one thing. 1.First of all I would like to know if you can capture and raise a wild duck or duckling.

Physically you can - but whether or not it is legal to do in your location or ethical are other questions.

And another question would be what are you goals? and would a 'wild raised in captivity' duck meet those goals? Sometimes getting animal breeds that were purposely selected to meet specific goals makes it a lot easier and more rewarding to reach them. For example, I would not expect a 'formerly wild' duck to lay many eggs while a runner duck produces more eggs than most chickens.

If you are looking for a pet duck and the breed you can 'grab' is not endangered in any way and it's not illegal to keep wild animals then sure, why not?

I understand the logic when you consider how many wild ducks are subject to hunters who are more into shooting with a drunk that providing food to survive.
I would discourage from a inputs vs output's point of view, your going to be on your own with undomesticated ducks and breeding for meat or eggs can come with downsides you can't see ahead.
There's enough to do which lines of ducks that have evolved alongside man for mutual benefit that I wouldn't considered it a standard beginning for the uninitiated.
My muscovies are a perfect example of a breed making a deal with man that has allowed it to range the globe vs it's natural climate of southern america.
I run around in all directions for them all year round, in exchange I can have 8 pounds of meat in 12 weeks. I couldn't even consider the dress out weight of a wild duck feeding any homesteading needs without having to kill allot of wild ducks.