How to access param values of widgets inside a dynamically defined WidgetBox?

Panel
6

maybe this link can help you.

With that help, i adapted to your example.

import panel as pn
import param
pn.extension()

class DynamicWidgetBox(param.Parameterized):
    options = param.ListSelector(objects= ['a','b','c','d'])

    def __init__(self, **param):
        super(DynamicWidgetBox, self).__init__(**param)
        self.col1 = pn.Column(*pn.panel(self.param), 
                                pn.Row())

    @param.depends('options', watch=True)
    def get_widgetBox(self):
        selects = []
        for v in self.options:
             selects.append(pn.widgets.MultiSelect(name=v, options=[1,2,3,4,5]))
        self.col1[2] = pn.WidgetBox(*selects, horizontal=True)

    def panel(self):
        return self.col1

DynamicWidgetBox().panel().servable()