How to add custom field in OutBound changeset?

If the updated picklist fields in question are custom fields, you'll want to select the "Custom Field" Component Type from the "Add to Change Set" page and proceed to locate the desired custom fields to be added to your change set. You should be able to sort the resultant list view by Name (i.e., a custom field's Field Label) or Type (i.e., the object to which a custom field belongs).

Standard Fields are not available as components for change sets. Neither are Standard Objects (as opposed to being able to add a Custom Object to a change set).

You will not be able to include Campaign Influence and Campaign search layout Campaigns Tab to your change set.

On a related note, when you include a Custom Object component in a change set, that Custom Object's search layouts are automatically included because they are a part of the custom object.