<aura:component implements="force:appHostable,lightning:isUrlAddressable,flexipage:availableForAllPageTypes,flexipage:availableForRecordHome,force:hasRecordId,forceCommunity:availableForAllPageTypes,force:lightningQuickAction" controller="AccountController" access="global" >
<aura:attribute type="campaign[]" name="acctList"/>
<aura:attribute name="mycolumns" type="List"/>
<aura:handler name="init" value="{!this}" action="{!c.fetchAcc}"/>
<lightning:datatable data="{! v.acctList }"
columns="{! v.mycolumns }"
keyField="id"
hideCheckboxColumn="true"/>
</aura:component>
Could you use
<aura:unescapedHtml value=""/>